Hot-rolled binary zinc-titanium alloy



Patented July 25, 1950 UNITED I 2,516,737 I HOT-ROLLED BINARYZINC-TITANIUM ALLOY 1 Thomas C." Wilson, Washington, D. 0., assignor toThe New Jersey Zinc Company, New York, N. Y., a corporation of NewJersey No Drawing. Application January 15, 1944, Serial No. 518,418

' 2 Claims. 1

This invention relates to binary zinc-titanium alloys, and particularlyto the alloys disclosed in my copending United $tates patent applicationSer. No. 460,933, filed October 6, 1942, noW aban' 2 loys attemperatures of from 190 to 300 C.,,temperatures of from 200 to 235 C.giving very satisfactory results. The hot rolling or mechanical workingof the invention may be a finishing opdoned. The present invention isconcerned with 5 oration consistin of say three or more passes theworking of such alloys and contemplates certhrough the rolls, and may bepreceded by either tain improvements in the mechanical working cold orhot rough rolling. and especially the rolling of such alloys.Creep'resistance or creep rate may be measured The binary zinc-titaniumalloys disclosed in and directly expressed as the precent elongation myaforementioned patent application contain or creep of a standard testpiece during a'unit of from 0.01% to 1.6%, and preferably from 0.05% stime, say one day, when subjected to a. dead load to 0.3%, titanium,with thebalance zinc, prefof, say, 8000 poundsper square inch (p. s. i.)at era-bly high-grade zinc, although zinc of the constant roomtemperature 0.). When the grade commonly used in commercial rolled zinccreep rate is so expressed, the lower values (permay be used. Thesealloys are conveniently l5 cent/days) represent the higher creepresist,- manufactured by first preparing a zinc-titanium 'ance. I preferto express the creep resistance hardener by adding about 4% of titaniummetal' as the inverse creep rate which is the number of to molten zincandholding under a boric acid units of time, say days, required toproduce an cover, with frequent stirring, at 750 CL until the elongationor creep of one percent (days/pertitanium is dissolved. The desiredtitanium con- 2 cent), whereby the more creep resistant alloy tent inthe binary zinc-titanium alloy is then (or material) has the higherinverse creep rate. readily obtained by adding the calculated amount Thefollowing Table I shows the mechanical of this hardener to apredetermined weight of properties and superior inverse creeprates ofmolten zinc. c three (Nos. 1, 2 and 3) hot-rolled zinc-titanium Thebinary zinc-titanium alloys of my afore- 25 alloys of the invention,contrasted with a zincmentioned patent application, when transformedcopper alloycontainin 1% copper. The zincto sheet or strip by suitablerolling procedure, titanium alloys were hot rolled to 0.02" in a 12"possess high creep resistance (resistanceto cold diameter mill with afinal coil temperature of flow), namely, resistance to prolonged staticabout 200 C. The bars rolled quite easily and loads well below theultimate limit. Cold work- 0 produced strip of good surface quality, Thebi or rolling tends to decrease the creep resistrolled strips weresubjected to the normal routine ance of these alloys, but their normalhigh creepv mechanical property tests including determinaresistance canbe substantially restored by subsetions of creep rate.

' Table I Tensile Elon- Inverse Creep Rates,D ays Analyzed s... e mendthan in iiiiiiii Per Cent Gauge scope namic per,

T1 Bal- In j Hard- Ductil- Per amezn Cent With Across With Across WithAcross 8,000 12,000 15,000 Grain Grain Grain Grain Grain Grain p. s. i.p. s. i. p. s. i.

0.023 119- .0. 320 -30. 2% 2 19,500 27,600 33.2 13.3 24.2 0.055 0.00390.021 20 0.300 37 3 2 20,100 20,900 29.5 12.0 100.0 1.05 0.023 0.022 220.295 40 4 2 21,300 30,000 28.3 11.3 1,120.0 4.05 0.077 0.018 17 0.28040 3% 2 23,700 30,000 35.0 8.7 1.95 0.10 NoTest 1 Alloys prepared with99.99%pure zinc.

2 Values represent the diameter of the bend in multiples of sheetthickness.

3 Hot rolled, analogous to Zn-Ti treatment.

Small values indicate better bending properties.

4 Tests not run to the usual fi-per cent total elongation. Valuesrecorded represent the slope of the line joining the origin of the curveof time vs. elongation with the final recorded point-values probablylower than true values.

cally working or rollin these z'inc titaniumal- 1 The data in Table Ishows the remarkable "creep resistance of the hot-rolled alloys of theinvention. At moderate loads (e. g. 8000 p. s.-i.)

the creep resistance of these alloys is astonishingly high, particularlyin the case of the alloy containing 0.23% titanium (No. 3).

As hereinbefore stated, I have found that the temperature of rollingexercises a very great effect upon the creep resistance or the rolledstrip. With a rolling temperature around 0., the inverse creep rate of azinc-titanium alloycontaining 0.12% titanium was 0.033 (days/percent)under a load of 12,000 p. s. i. With a rolling temperature around 190 C.the inverse creep rate of the same alloy was 0.72, and with a rollingtemperature of around 210 C. the inverse creep rate was 1.76. The effectof rolling temperature upon the creep resistance of the rolled alloy isshown in the following tables in which Table II gives the schedule ofthe rolling operations orv 5 specimens of a zinc-titanium alloycontaining 0.12% titanium, and Table III gives the inverse creepresistance rate of the resulting rolled strips.

The preliminary or rough rolling schedule was the same for each specimen(A to E) and reduced the specimens from slabs 7"x14"x1 :to agauge ofapproximately 0.09" in ten passes through therolls. The first horizontalline of Table II is the temperature of the rolls, the second horizontalline is the starting temperature of the alloy specimens, D and E- beingpreheated in order to attain the higher final coil temperatures. Thespecimens were given three passes (four for A) through the rolls toefiect a reduction in gauge from about 0.09" to about 0.02" (0.015" forC). The last horizontal line of the table is the final coil temperatureof the rolled strip after the final rolling pass.

Table II A B C D E 140-160" C. 170-190 G. FIG-190 C. 170-190 0. 170-1900. Room Room Room 140 0. 140 C.

Table III Inverse Final coil Creep Rate. Specimen Tgntgeer' i z gg p. s.1.

The influence of hot rolling upon the creep resistance of thezinc-titanium alloys is further illus'trated by Table IV, in which thehot rolled alloy (0.12 titanium) is contrasted with the cold vrolledalloy, and with hot and cold rolled zinc .copper alloy (1% copper).

From the foregoing examples, it will be seen that the hot rolled orworked alloys of the inventionpossess remarkably high creepresistance.The line of demarcation between cold and hot rolling, so far as theeffect upon creep resistance is concerned, seems to be in theneighborhood of 160-180 C. With rolling temperatures below thattemperature range, the creep resistance is not unusual. With rollingtemperatures above that temperature range, a significant and sharpincrease in creep resistance is attained. The contemplated conditions ofhot rolling can be established by preheating the alloy or by heating therolls so that the thermal conditions during rolling impart a finaltemperature of 190 to 300 C. to the alloy passing from the final roll(final coil temperature). It is not necessary, and in practice notlikely, that the contemplated hot rolling temperature be maintainedduring each pass of the complete rolling schedule. The advantages of theinvention are satisfactorily attained where the final coil temperatureis within the contemplated hot rolling temperature range.

The data in Table IX reveal theunusual effect in the zinc-titanium alloyof cold rolling effecting a softening and weakening as compared with hotrolled material. The work hardening revealed in the 1% copper alloy is,of course, the normal result.

Photomicrographs' of the hot and cold rolled zinc-titanium alloy of theinvention show the metal to he apparently free of cold working in thecold rolled state, an observation that is consistent with the physicalproperties of the metal.

Redraw tests showed that as many as four redraws could be made withoutintermediate anneals, and with at least recovery of unfracturedmaterial. Thus, it is evident that the alloy does not work harden.Another interesting property of the alloy is the appearance of a highpopulation of basal planes normal to the rolling plane and lying in therolling direction.

Contrary to experience with zinc, the zinctitanium alloy has been foundnot to grow excessively large grains when annealed. Anneals up to, 24hours duration at temperatures up to 400 C. failed to produce relativelycoarse grain structures. Moreover, it has been found that ductility andother properties are not harmed by annealing and, significantly, thehigh creep resistance noted inthe hot rolled alloy which was sharplyreduced by cold working was found to be largely restored bysuitable heattreatment.

I claim:

1. A. binary zinc-titanium alloy product containing from 0.01% to 1.6%titanium and having been subjected to a finishing treatment consistingof hot rolling at a temperature within the range of C. to 300 C.

2. A binary zinc-titanium alloy product containing from 0.05% to 0.30%titanium and having been subjected to a finishing treatment consistingof hot rolling at a temperature within the range of from 200 C. to 235C.

THOMAS C. WILSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 979,393 Rossi Dec. 20, 19101,020,512 Rossi Mar. 19, 1912 1,835,450 Anderson Dec. 8, 1931 1,888,567Pierce Nov. 22, 1932 2,048,288 Pierce Jul 21, 1936 2,169,441 Winter Aug.15, 1939 2,317,179 Daesen Apr. 20, 1943 OTHER REFERENCES MetalsHandbook, 1939 edition, pages 1737, 1765; pub. by American Society forMetals, Cleveland, Ohio.

. Certificate of Correction Patent No. 2,516,737 July 25, 1950 THOMAS 0.WILSON It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfollows:

Column 2, line 9, for precent read percent; line 51, for shows readshow; column 4, line 16, for Table IX read Table IV;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOflice.

Signed and sealed this 17th day of October, A. D. 1950.

THOMAS F. MURPHY,

Assistant Gommz'ssz'oner of Patents.

1. A BINARY ZINC-TITANIUM ALLOY PRODUCT CONTAINING FROM 0.01% TO 1.6%TITANIUM AND HAVING BEEN SUBJECTED TO A FINISHING TREATMENT CONSISTINGOF HOT ROLLING AT A TEMPERATURE WITHIN THE RANGE OF 190*C. TO 300*C.